This invention relates to solutions for the production of fire resistant glazings, interlayers produced from said solutions, fire resistant glazings and laminated fire resistant glazings comprising said interlayers and methods for the preparation of said solutions, interlayers, fire resistant glazings and laminated fire resistant glazings. This invention also relates to buildings and fire resistant glazing assemblies incorporating said fire resistant glazings.
Glass laminates incorporating an intumescent inorganic silicate interlayer sandwiched between two opposed panes of glass are sold under the trade marks PYROSTOP and PYRODUR by the Pilkington group of companies. When such laminates are exposed to a fire the inorganic interlayer intumesces and expands to form a foam layer. The foam provides a thermally insulating layer which protects the pane of glass remote from the fire so that the structural integrity of the glass unit, which acts as a barrier preventing the propagation of the fire, is maintained for a longer period. Glass laminates incorporating such intumescent interlayers have been used successfully as fire resistant glass structures. These laminates may comprise more than two panes of glass sandwiching more than one intumescent interlayer. Laminates comprising up to eight intumescent interlayers have been employed. These multi layered laminates are relatively thick and correspondingly expensive.
The intumescent inorganic layer is normally formed from a sodium silicate waterglass or a mixture thereof with potassium or lithium silicate waterglasses. The layer is commonly formed by preparing a solution of the silicate, spreading that solution on the surface of the glass and drying excess water from the solution so as to form the intumescent inorganic layer.
WO 2007/144369 describes the use of bubble initiation elements in intumescent layers in order to avoid glass bursts due to localised accumulation of water vapour. The initiation elements may be silica or glass particles and are said to support the homogeneous distribution of bubbles.